From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752881Ab1LSL77 (ORCPT ); Mon, 19 Dec 2011 06:59:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:1025 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752706Ab1LSL74 (ORCPT ); Mon, 19 Dec 2011 06:59:56 -0500 Message-ID: <4EEF2729.6080501@redhat.com> Date: Mon, 19 Dec 2011 13:59:37 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111115 Thunderbird/8.0 MIME-Version: 1.0 To: Nikunj A Dadhania CC: Ingo Molnar , peterz@infradead.org, linux-kernel@vger.kernel.org, vatsa@linux.vnet.ibm.com, bharata@linux.vnet.ibm.com Subject: Re: [RFC PATCH 0/4] Gang scheduling in CFS References: <20111219083141.32311.9429.stgit@abhimanyu.in.ibm.com> <20111219112326.GA15090@elte.hu> <4EEF2382.4010605@redhat.com> <87hb0wbx0p.fsf@abhimanyu.in.ibm.com> In-Reply-To: <87hb0wbx0p.fsf@abhimanyu.in.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/19/2011 01:50 PM, Nikunj A Dadhania wrote: > On Mon, 19 Dec 2011 13:44:02 +0200, Avi Kivity wrote: > > On 12/19/2011 01:23 PM, Ingo Molnar wrote: > > > What's behind this huge speedup? Does ebizzy use user-space > > > spinlocks perhaps? Could we do something on the user-space side > > > to get a similar speedup? > > > > kvm tries to detect spinlocks (by trapping repeated executions of PAUSE) > > and yield to a related vcpu. It's far from perfect however, and relies > > on the spinlock code using PAUSE. > > > Avi, is this soft-PLE kind of thing? No, hard PLE, see the calls to yield_to. -- error compiling committee.c: too many arguments to function